Several newspapers have today reported that cancer rates have risen over the past two decades. Cancer rates in the middle-aged “have jumped by almost a fifth in a generation”, according to...

Several newspapers have today reported that cancer rates have risen over the past two decades. Cancer rates in the middle-aged “have jumped by almost a fifth in a generation”, according to The Daily Telegraph, which says that the increase “is thought to be mainly due to better detection of cancers rather than people adopting more unhealthy lifestyles”. The Sun takes the alternate view, saying that doctors are “blaming the rise on obesity and home boozing”. The Daily Mail similarly suggests that lifestyle changes are to blame.

What is the basis for these current reports?

Newspapers have reported a rise in cancers based on new figures compiled by Cancer Research UK (CRUK), which compares the rates of cancer in Great Britain in 1979 and 2008. This is part of a new national campaign being launched today by CRUK, aimed at highlighting the importance of publicly funded research.

What are the report’s findings?

The rates of new cancer diagnoses were reported to have increased by 16% in men and 34% in women in Great Britain between the 1977-1979 and 2006-2008 reporting periods. This equated to a rise from 368.3 to 416.7 cases per 100,000 men, and from 273.9 to 365.7 cases per 100,000 women.

This rise was reported to have occurred almost entirely before the late 1990s - the rates are reported to have stayed relatively stable over the past decade in Great Britain, at around 355 cases per 100,000 women and 415 cases per 100,000 men.

The increases seen between 1979 and 2008 varied across age groups:

The highest rate of new diagnoses is among people aged 75 and over. The rate of new diagnoses in over-75s increased from 1,808 per 100,000 to 2,319 per 100,000 (a 28% rise).

In people aged 60 to 74, new diagnoses rose from 1,075.9 per 100,000 to 1,370 per 100,000 (a 27% rise).

In people aged 40 to 59, new diagnoses rose from 329.1 per 100,000 in 1979 and 388.1 per 100,000 in 2008 (an 18% rise).

The lowest rate of new diagnoses is among people aged 0 to 39. The rate in this age group increased from 29.5 per 100,000 in 1979 and 41.2 per 100,000 in 2008 (a 40% rise).

What do the stats say about middle-aged people?

The CRUK press release and most media coverage focus on the rates of cancer in middle-aged individuals. It reports that 44,000 people aged 40 to 59 years old were diagnosed with cancer in Britain in 1979. This number rose to 61,000 in 2008. Increases have been seen in both men and women, with almost 20,000 cases of cancer in men and more than 24,000 in women in 1979, rising to 24,000 men and more than 36,500 women in 2008.

When looking at the rates of new diagnoses of specific cancers among people aged 40 to 59 years old, CRUK reports that:

the rate of new cases of breast cancer in women has increased from 134 per 100,000 women in 1979 to 215 per 100,000 in 2008

the rates of new cases of prostate cancer among men has increased from 8 per 100,000 in 1979 to 51 per 100,000 in 2008

more encouragingly, the rates of new cases of lung cancer in men dropped from 93 per 100,000 in 1979 to 35 per 100,000 in 2008

However, CRUK say that the number of people surviving cancer has doubled since the 1970s. There were 215.2 deaths from cancer per 100,000 people in Great Britain in 1979, which fell to 175.4 deaths from cancer per 100,000 people in 2008.

Why are the rates on the increase?

The causes of these increases were not directly investigated.

However, CRUK say that one factor contributing to these increases is likely to be higher rates of detection due to the NHS breast cancer screening programme and the PSA test for prostate cancer. The raw data behind these stats also needs to be placed into context: these particular cancer diagnosis rates are drawn from the datasets for England from the Office of National Statistics and similar datasets from registries in Scotland, Northern Ireland and Wales. The ONS urges caution when interpreting its data, particularly when looking at trends across time, or differences across regions.

For example, since 1993 it has been mandatory for NHS staff to report information on cancer diagnoses to cancer registries. Prior to this, the information may be less complete, and therefore not necessarily reflective of the true rate of cancer. Even for more recent years, cancer registry data may not be complete.

Some newspapers have suggested that these rises are due to modern changes in lifestyle, with people now adopting poorer diets or getting less exercise than in past decades. While this particular dataset cannot confirm this view, it is known that certain lifestyle factors do influence risk of cancer, such as smoking, obesity, diet, and alcohol consumption.

Therefore changes in these habits over time could influence cancer rates. Maintaining a healthy diet and weight, not smoking, and reducing our alcohol consumption are ways that individuals can try to cut down their risk of cancer.